I second therapy! Both marriage counseling and individual therapy really helped my husband and I communicate better. I think the biggest thing we learned was that when we’re not communicating, we’re just kind of guessing at what the other person is feeling and thinking. And then we create this narrative around that, and by the time we do talk about it, we already have this story in our own heads that we’re reacting to rather than the actual truth. Therapy also allowed us to dig around together into our own pasts. For example, in couples therapy we realized that one of my husband’s triggers is a certain time of year because he associates it with loss. And so that explains why he often slips up during that time.
The first step though is getting both people onboard and willing to do therapy, which is a hurdle on its own. So if that’s not an option, I’d say that when there’s a lack of communication, just try to not take things personally and don’t assume you know what’s wrong with them. We never know what’s really going on with the other person unless they tell us, and making up our own stories based on their behaviors, tone of voice, etc. is not helpful.